Magnesium base alloy



Patented Nov. 12, 1940 um'rsn STATES FATE MAGNESIUM BASE ALLOY No Drawing, Application November 13, 1939, Serial No. 304,134

. 3 Claims.

The invention relates to magnesium base alloys. It more particularly concerns alloys of this nature having a high degree of formability coupled with other improved physical properties,

such as increased tensile and yield'strengths.

. Magnesium alloys are being widely used in various structural and mechanical arts where a light weight metal is highly desirable, such as for use in making castings, forgings, and the like.

However, the use of these alloys in the rolled form to make sheet metal articles requiring forming operations such as bending, drawing and the like has not progressed as rapidly due to the fact that in general alloys having good forml5 ability, permitting relatively sharp bends to be made without the article developing external cracks, usually have inferior tensile and yield strengths.

It is accordingly the principal object of this 0 invention to provide a magnesium base alloy which may be made into rolled sheet or the like, possessing a high degree of ductility or formability together with high strength characteristics.

Other objects and advantages of the invention will be apparent as the description of the'invention proceeds.

My invention resides in the discovery that a acteristics, is manifest over the entire range of composition indicated, I have found that in general the preferred combination of properties, such as satisfactory ductility for forming operations together with high tensile and' yield strengths, is found in alloys containing from 0.5 to 4 per cent of silver, 6 to 12 per cent of cadmium, and from 0.5 to 4 per cent of zinc. In general the alloys containing the higher percentages of the alloying ingredients have higher strength properties, making them very suitable for use in casting operations as well as forming operations.

The specific proportion of each alloying metal and the total amount of the added metals to be 15 employed in the new alloy depends upon the use for which the alloy is intended. In general it is preferable to employ an alloy containing more than about '75 per cent magnesium and less than 25 per cent of the total added metals.

The following table, which lists some of the properties of rolled sheet metal made from my new alloy, as well as the properties of sheet metal made from related ternary alloys, illustrates the improvement in yield strength, tensile strength, and ductility or formability, as represented by the per cent elongation increase, of .my new alloy over that of the closely related alloys.

Table 30 ggigggfgggggf Annealed 001111011411.

1; Yietg in t i l i l l t l 1 t i H s t A 0 Zn 5 ten 8 rang n e onge on s reng n s tong n g d lbs./s%1. in. lbs./sq. in. in 2 inches lbs./sq. in. lbs/sq. in. 35

4. 0 1. 0 10,000 00,000 15 20, 000 00, 000 2.0 5.0 0.0 11,000 00,000 20 05,000 42,000 4. 0 1.0. 10,000 00,000 15 20,000 00,000 5.0 5.4 1.0 26,000 08,000 15 40,000 40,000 0 s 0.0 11,000 02,000 11 02,000 01,000 8.7 0.0 10,000 00,000 11 00,000 00,000 0.0 0.4 10,000 01,000 15 28,000 25,000 0.0 0.0 0.0 21,000 05,000 24 04,000 41,000 0. 0 s. 4 10,000 01. 000v 15 20,000 05,000 0.8 0.4 5.5 21,000 40,000 10 41,000 48,000

magnesium base alloy composed of from 0.5 to 1 The properties listed in the above table under 10 percent of silver, from 1 to 15 per cent of the section headed by the term annealed were 5 cadmium, and from 0.1 to 10 per cent of zinc, the balance being substantially all magnesium, is endowed with the aforementioned properties. While the property of improved formability or ductility, associated with high strength charobtained by first rolling the alloys at a temperature between about 500 to 600 F., and-thereafter annealing them at various temperatures through a temperature range of from 400 to 800 F. The

properties selected for the table were those of 55 the section headed cold rolled" were obtained by subjecting specimens 01' the alloys which had been hot rolled at a. temperature of from 500 to 600 F. to additional rolling in the cold state to bring about a total reduction in thickness of from 2 to 10 per cent. The properties selected for the table were those of the cold rolled speci= mens which showed the greatest tensile and yield strengths, while having at least a, l per cent elongation in 2 inches.

By comparison of the properties listed in the above table, it will be observed that the combined properties of my new quaternary alloy are su perior to those of the parent ternary elloys having similar percentages of alloying ingredients. For example, it will he noted that in general the elongation is greatly improved, while the yield strength and tensile strength in both the annealed and cold rolled state shows on improvement over that of the related alloys. Similarly, an innprovenient in properties will be noted in the remining portion of the composition range.

While the new alloy is most useful in moinght form, such as sheets, due to its iormeloility char ecteristics, it may elso he suitably used in making costings, forgings, extruded terms, and the like. It is further pointed out that my new alloy is amenable to solution end precipitation heat treatments, which, accordingly, modify its properties.

My new alloys may be prepared by any of the methods usually employed for melting and alloying metals with magnesium, such as by adding the alloying rncterlels singly or jointly to e, hath of molten magnesium, which is preferobly protected from oxidation by c suitable flux.

i claim:

i. A magnesium hese alloy containing from 0.5 to it per cent of silver, from 1 to 15 per cent of cadmium, and from 0.1 to 10 per cent of mic. the balance being magnesium.

2. A magnesium hose alloy containing from 0.5 to l per cent of silver, from 6 to 12 per cent of cedxnium, end from on to per cent of zinc, the balance being magnesium.

3. A magnesium hose alloy conteiningirom l to 3 per cent of giver, from 5 to 12 per cent of cadmium, and irom 0.5 to e per cent of zinc, the

balance being megnesinrn J OHN C. MCDONALD.

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